US4783993A - Tire pressure sensor for motor vehicles - Google Patents

Tire pressure sensor for motor vehicles Download PDF

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Publication number
US4783993A
US4783993A US07/095,536 US9553687A US4783993A US 4783993 A US4783993 A US 4783993A US 9553687 A US9553687 A US 9553687A US 4783993 A US4783993 A US 4783993A
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US
United States
Prior art keywords
tire
pressure
diaphragm
chamber
pressure chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US07/095,536
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English (en)
Inventor
Haas Lothar
Hettich Gerhard
Schmid Hans-Dieter
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Robert Bosch GmbH
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Robert Bosch GmbH
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Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Assigned to ROBERT BOSCH GMBH, POSTFACH 50, D-7000 STUTTGART 1, GERMANY A LIMITED LIABILITY COMPANY OF GERMANY reassignment ROBERT BOSCH GMBH, POSTFACH 50, D-7000 STUTTGART 1, GERMANY A LIMITED LIABILITY COMPANY OF GERMANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SCHMID, HANS-DIETER, WALTER, BERTHOLD, HAAS, LOTHAR, HETTICH, GERHARD, KAMP, MANFRED, SCHRUMPT, HANS
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C23/00—Devices for measuring, signalling, controlling, or distributing tyre pressure or temperature, specially adapted for mounting on vehicles; Arrangement of tyre inflating devices on vehicles, e.g. of pumps or of tanks; Tyre cooling arrangements
    • B60C23/02—Signalling devices actuated by tyre pressure
    • B60C23/04—Signalling devices actuated by tyre pressure mounted on the wheel or tyre
    • B60C23/0408—Signalling devices actuated by tyre pressure mounted on the wheel or tyre transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00—Switches operated by change of a physical condition
    • H01H35/24—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/26—Details
    • H01H35/2671—Means to detect leaks in the pressure sensitive element

Definitions

  • the invention relates a tire pressure sensor for motor vehicles. It is known from DE-OS 28 32 447 to screw in a tire pressure sensor at the circumference of a wheel rim, which tire pressure sensor comprises a pressure switch for monitoring the air pressure in the tire and is actuated by the tire pressure.
  • the pressure switch includes, on the one hand, an electrically conducting diaphragm, which closes a reference pressure chamber in the direction of the tire, and, on the other hand, a contact pin which is sealed in a glass bushing so as to be electrically insulated and is contacted by the middle area of the diaphragm when there is sufficient air pressure in the tire in order to close an electric circuit.
  • the reference pressure chamber is filled to a desired reference pressure with air or nitrogen via a duct and is then closed so as to be pressure-sealed.
  • the reference pressure is selected in such a way that the diaphragm contacts the end of the contact pin when there is sufficient air pressure in the tire.
  • the diaphragm rises off the contact pin and opens an oscillating circuit, which comprises a coil and a capacitor, which is arranged in the tire pressure sensor.
  • the evaluating circuit By means of a high-frequency oscillation of the evaluating circuit, which is arranged so as to be fixed in the vehicle, it can be determined whether or not the pressure switch is closed with a signal receiver arranged in the proximity of the tire when passing the tire pressure sensor with each revolution of the wheel.
  • the present solution attempts to transmit a signal to the evaluating circuit when a leak occurs in the reference pressure chamber using simple means.
  • the tire pressure sensor has the advantage that the diaphragm rises off the contact pin already when there is a pressure compensation between pressure in the reference chamber and the tire pressure and accordingly transmits an alarm signal to the evaluating circuit, i,e, the contact is open in the state of the absence of differential pressure. If the pressure compensation occurs because of a leak, insufficient pressure will be signalized again after a short time when refilling the tire (because of pressure compensation). This does not happen when there is inadequate tire pressure and during refilling.
  • the coil and the capacitor of the tire pressure sensor are arranged in an oscillating circuit chamber directed toward the signal receiver, which latter is arranged in the proximity of the wheel so as to be stationary, it is advisable that one end of the contact pin and a connecting wire of the reference pressure chamber project through a seal in the oscillating circuit chamber.
  • FIG. 1 shows a partial sectional view of a vehicle wheel with the tire pressure sensor, according to the invention, which is inserted in the rim;
  • FIG. 2 shows a cross section through the tire pressure sensor, according to the invention, in enlarged presentation
  • FIG. 3 shows a greatly enlarged switching area of the diaphragm with the contact pin
  • FIG. 4 shows the clamping point of the reference chamber at the sensor housing, which clamping point is shown as greatly enlarged.
  • FIG. 1 The part of a motor vehicle wheel in reduced scale is shown in cross section in FIG. 1 and is designated by 10. It shows a tire 11 which is fastened on a wheel rim 12. At an inwardly directed portion of the wheel rim 12, a tire pressure sensor 13 is screwed into a threaded borehole 14 of the wheel rim 12. At a short distance from the latter a signal receiver 15 is fastened in the area of the tire pressure sensor 13 at the wheel suspension of the vehicle, not shown; the front side of the signal receiver 15 is directed toward the tire pressure sensor 13 and excites a high-frequency oscillation in the tire pressure sensor 13 when the latter passes during every revolution of the vehicle wheel 10.
  • the construction of the tire pressure sensor 13 is shown in FIG. 2. It includes a sensor housing 16 of special steel which has a threaded projection 17 for fastening at the wheel rim 2.
  • the sensor housing 16 is open in the front toward the tire 11.
  • a wide ring shoulder 18 is located in the interior in the middle area of the sensor housing 16.
  • a sealing ring 19, a supporting ring 20 of plastic, a reference pressure chamber forming element of steel, a spacing ring 22 of fiber plastic material, and a perforated covering disk 23 are inserted in the sensor housing 16 and clamped in the sensor housing 16 by means of the ring shoulder 18 and a flange 24 at the front end face of the sensor housing 16.
  • the reference pressure chamber 21a formed by element 21 is closed toward the interior of the tire 11 by means of a flat diaphragm 29.
  • a contact pin 30 is fastened with a glass bushing 31 so as to be pressure-sealed and is fastened in the reference pressure chamber forming element 21 so as to be electrically insulated.
  • Pin 30, with the contact carries a welded on contact ball 32 of gold at its front end.
  • the contact surface of the contact ball 32 is processed together with the annular supporting surface 33 of the element 21 for the diaphragm 29 in such a way that there is an air gap X of approximately 0.03 mm between the contact ball 32, and the middle area of the diaphragm 29 in order to check leaks in the reference pressure chamber 21a in the pressureless state.
  • FIG. 3 shows this by means of a greatly enlarged view of the contact area between the diaphragm 29 and the contact pin 30. Only then is the diaphragm 29 welded on externally at the front side on the supporting surface 33 so as to be pressure-sealed and free of tension by means of a laser beam.
  • the reference pressure chamber 21a is filled with air or nitrogen with the required reference pressure via a filling duct 34.
  • the filling duct 34 is then closed so as to be pressure-sealed by means of a ball 35 which is pressed in or welded therein.
  • a connecting wire 36 is welded on at the reference pressure chamber forming element 21 by
  • the reference pressure chamber forming element 21 is inserted in the supporting ring 20 in such a way that it rests on top of a ring wall 38 of the carrying ring 20 by its radial collar 37 which is formed on at its outer circumference.
  • the supporting ring 20 has a collar 39 which projects through the ring shoulder 18 of the steel housing 16 and encloses the connecting wire 36 and the contact pin 30.
  • the interior of the collar 39 is filled with a sealing substance 40, e.g. a polyurethane, which encloses the contact pin 30 and the connecting wire 36 in the area of the collar 39 so as to be airtight.
  • a covering cap 41 closes the oscillating circuit chamber 35 outwardly in that it rests on the lower end of the sensor housing 16 with an additional sealing ring 42 and is fastened at a ring shoulder 43 by means of a flange 44 of the sensor housing 16.
  • the connecting wire 36 is contacted at its outer end with a connection 45 of the capacitor, not shown, whose other connection 46 is connected with an end of the toroidal coil 26.
  • the other end of the toroidal coil 26 is finally contacted with the free end of the contact pin 30.
  • the compressed air In order to ensure a complete leakage testing of the reference pressure chamber 21, the latter must be completely surrounded by the compressed air in the tire. This is achieved in that the compressed air first reaches the diaphragm 29 of the reference pressure chamber 21 through openings 47 in the covering disk 23. As shown in FIG. 4, the compressed air reaches a gap 49 between the steel housing 16 and the spacing ring 22 via a radial notch 48 in the outer area at the underside of the covering disk 23 and, from there, arrives at a radial depression 50 which is worked into the ring wall 38 of the carrying ring 20 and is open toward the collar 37 of the reference pressure chamber 21. From there, the compressed air finally arrives at the rear side of the reference pressure chamber forming element 21.
  • the radial gap 49 between the sensor housing 16 and the spacing ring 22 is formed in that the spacing ring 20, like the collar 37 of the element 21, has a smaller outer diameter than the receptacle of the sensor housing 16 in this area.
  • the invention is not limited to the embodiment example, since in many cases a leakage monitoring of the diaphragm welding at the reference pressure chamber is sufficient, and this is already ensured in that the revolving welding seam at the diaphragm is reached by the compressed air in the tire.
  • the contact spacing X between the contact pin and the diaphragm can be effected with a different magnitude and in a different manner, e.g. by means of upsetting the contact ball 32 after welding on the diaphragm 29 prior to filling the reference pressure chamber 21 with gas. It is essential that when the pressure is equal on both sides of the diaphragm 29, the latter rises from the contact pin 30 in order to interrupt the electric circuit.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Measuring Fluid Pressure (AREA)
US07/095,536 1985-12-12 1986-11-05 Tire pressure sensor for motor vehicles Expired - Fee Related US4783993A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3543866 1985-12-12
DE19853543866 DE3543866A1 (de) 1985-12-12 1985-12-12 Reifendrucksensor fuer kraftfahrzeuge

Publications (1)

Publication Number Publication Date
US4783993A true US4783993A (en) 1988-11-15

Family

ID=6288240

Family Applications (1)

Application Number Title Priority Date Filing Date
US07/095,536 Expired - Fee Related US4783993A (en) 1985-12-12 1986-11-05 Tire pressure sensor for motor vehicles

Country Status (5)

Country Link
US (1) US4783993A (de)
EP (1) EP0248821B1 (de)
JP (1) JPS63501864A (de)
DE (2) DE3543866A1 (de)
WO (1) WO1987003547A1 (de)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4954677A (en) * 1986-11-20 1990-09-04 Robert Bosch Gmbh Tire pressure sensor for motor vehicles
US4954806A (en) * 1990-01-17 1990-09-04 Hwang Feng Lin Warning device for the inadequate tire air pressure
US5289160A (en) * 1991-09-30 1994-02-22 Fiorletta Carl A Tire pressure monitoring system
US5540268A (en) * 1991-12-17 1996-07-30 Mittal; Chander Apparatus for repeatable adjustment of tire pressure
US5717135A (en) * 1991-09-30 1998-02-10 Carl A. Fiorletta Tire pressure monitoring system utilizing a pressure activated transducer and sensor
US5824891A (en) * 1996-04-03 1998-10-20 Ssi Technologies, Inc. Method and apparatus for effiviently phase modulating a subcarrier signal for an inductively coupled transponder
US5838229A (en) * 1995-07-18 1998-11-17 Schrader-Bridgeport International, Inc. Remote tire pressure monitoring system employing coded tire identification and radio frequency transmission and enabling recalibration upon tire rotation or replacement
US20050087228A1 (en) * 2003-10-24 2005-04-28 Lear Corporation Snap-in grommet for a valve stem assembly
US20050087006A1 (en) * 2003-10-24 2005-04-28 Lear Corporation Attachment mechanism for a tire monitoring system
US20050087229A1 (en) * 2003-10-24 2005-04-28 Lear Corporation Snap-in grommet for a valve stem assembly
US20050087007A1 (en) * 2003-10-24 2005-04-28 Lear Corporation Tire monitor system with spring retention clip
US20050092076A1 (en) * 2003-11-04 2005-05-05 Lear Corporation Tire pressure sensing component for detecting air pressure and related method
US6904795B1 (en) 2004-09-14 2005-06-14 Lear Corporation Sealed mounting of tire monitoring assembly
US6952955B1 (en) 2004-07-28 2005-10-11 Lear Corporation Adjustable mounting of tire monitoring assembly
US20100238011A1 (en) * 2009-03-19 2010-09-23 Carr William L Sensor Mount With Self-Tightening Device

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3813846A1 (de) * 1988-04-23 1989-11-02 Bosch Gmbh Robert Reifendrucksensor fuer kraftfahrzeuge
DE3822662A1 (de) * 1988-07-05 1990-01-11 Bosch Gmbh Robert Pneumatisch betaetigbarer druckschalter und verfahren zu seiner herstellung
DE3841995C1 (en) * 1988-12-14 1990-06-13 Moto Meter Ag, 7250 Leonberg, De Pressure switch for monitoring the pressure in the tyre of a motor vehicle wheel
DE3926245A1 (de) * 1989-08-09 1991-02-14 Bosch Gmbh Robert Reifendrucksensor fuer kraftfahrzeuge
DE3930813A1 (de) * 1989-09-14 1991-03-28 Wabco Westinghouse Fahrzeug Einrichtung zur reifendruck-ueberwachung
DE3934415A1 (de) * 1989-10-14 1991-04-18 Wabco Westinghouse Fahrzeug Einrichtung zur ueberwachung der dichtigkeit einer gasgefuellten kammer
JPH0481309A (ja) * 1990-07-24 1992-03-16 Nippondenso Co Ltd タイヤ空気圧検出装置
DE4105580C1 (en) * 1991-02-22 1992-04-02 Mercedes-Benz Aktiengesellschaft, 7000 Stuttgart, De Vehicle tyre filler valve - incorporates pressure indicator with chamber divided into two by membrane

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4071724A (en) * 1975-04-21 1978-01-31 Compagnie Generale Des Etablissements Michelin Tire pressure variation detector
GB2019651A (en) * 1978-04-25 1979-10-31 Pruss G Apparatus for providing an indication of a drop in pressure in a pneumatic tyre fitted to a motor vehicle
US4701742A (en) * 1985-03-01 1987-10-20 Dr. Ing. H.C.F. Porsche Aktiengesellschaft Pneumatic pressure switch for tire pressure monitor

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3185785A (en) * 1961-04-13 1965-05-25 Howard Irma Amelie Combined inflation valve and circuitclosing mechanism for pneumatic tires
IT998462B (it) * 1973-08-23 1976-01-20 Pirelli Cerchio per pneumatici con trasduttore di segnali
DE3004493A1 (de) * 1980-02-07 1981-08-13 Continental Gummi-Werke Ag, 3000 Hannover Vorrichtung zur ermittlung des druckes bei luftbereiften fahrzeugraedern

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4071724A (en) * 1975-04-21 1978-01-31 Compagnie Generale Des Etablissements Michelin Tire pressure variation detector
GB2019651A (en) * 1978-04-25 1979-10-31 Pruss G Apparatus for providing an indication of a drop in pressure in a pneumatic tyre fitted to a motor vehicle
US4701742A (en) * 1985-03-01 1987-10-20 Dr. Ing. H.C.F. Porsche Aktiengesellschaft Pneumatic pressure switch for tire pressure monitor

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4954677A (en) * 1986-11-20 1990-09-04 Robert Bosch Gmbh Tire pressure sensor for motor vehicles
US4954806A (en) * 1990-01-17 1990-09-04 Hwang Feng Lin Warning device for the inadequate tire air pressure
US5289160A (en) * 1991-09-30 1994-02-22 Fiorletta Carl A Tire pressure monitoring system
US5717135A (en) * 1991-09-30 1998-02-10 Carl A. Fiorletta Tire pressure monitoring system utilizing a pressure activated transducer and sensor
US5540268A (en) * 1991-12-17 1996-07-30 Mittal; Chander Apparatus for repeatable adjustment of tire pressure
US5838229A (en) * 1995-07-18 1998-11-17 Schrader-Bridgeport International, Inc. Remote tire pressure monitoring system employing coded tire identification and radio frequency transmission and enabling recalibration upon tire rotation or replacement
US5824891A (en) * 1996-04-03 1998-10-20 Ssi Technologies, Inc. Method and apparatus for effiviently phase modulating a subcarrier signal for an inductively coupled transponder
US5844130A (en) * 1996-04-03 1998-12-01 Ssi Technologies Apparatus for maintaining a constant radial distance between a transmitting circuit and an antenna coil
US5939977A (en) * 1996-04-03 1999-08-17 Ssi Technologies, Inc. Method and apparatus for synchronizing to a data stream for an inductively coupled transponder
US6304610B1 (en) 1996-04-03 2001-10-16 Ssi Technologies, Inc. Method and apparatus for synchronizing to a data stream for an inductively coupled transponder
US20050087228A1 (en) * 2003-10-24 2005-04-28 Lear Corporation Snap-in grommet for a valve stem assembly
US20050087006A1 (en) * 2003-10-24 2005-04-28 Lear Corporation Attachment mechanism for a tire monitoring system
US20050087229A1 (en) * 2003-10-24 2005-04-28 Lear Corporation Snap-in grommet for a valve stem assembly
US20050087007A1 (en) * 2003-10-24 2005-04-28 Lear Corporation Tire monitor system with spring retention clip
US6945104B2 (en) 2003-10-24 2005-09-20 Lear Corporation Attachment mechanism for a tire monitoring system
US7086412B2 (en) 2003-10-24 2006-08-08 Lear Corporation Snap-in grommet for a valve steam assembly
US7086411B2 (en) 2003-10-24 2006-08-08 Lear Corporation Snap-in grommet for a valve stem assembly
US20050092076A1 (en) * 2003-11-04 2005-05-05 Lear Corporation Tire pressure sensing component for detecting air pressure and related method
US7028541B2 (en) 2003-11-04 2006-04-18 Lear Corporation Tire pressure sensing component for detecting air pressure and related method
US6952955B1 (en) 2004-07-28 2005-10-11 Lear Corporation Adjustable mounting of tire monitoring assembly
US6904795B1 (en) 2004-09-14 2005-06-14 Lear Corporation Sealed mounting of tire monitoring assembly
US20100238011A1 (en) * 2009-03-19 2010-09-23 Carr William L Sensor Mount With Self-Tightening Device
US7937998B2 (en) 2009-03-19 2011-05-10 Deere & Company Sensor mount with self-tightening device

Also Published As

Publication number Publication date
EP0248821B1 (de) 1989-05-03
EP0248821A1 (de) 1987-12-16
DE3543866A1 (de) 1987-06-19
DE3663120D1 (en) 1989-06-08
JPS63501864A (ja) 1988-07-28
WO1987003547A1 (en) 1987-06-18

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AS Assignment

Owner name: ROBERT BOSCH GMBH, POSTFACH 50, D-7000 STUTTGART 1

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:KAMP, MANFRED;SCHRUMPT, HANS;WALTER, BERTHOLD;AND OTHERS;REEL/FRAME:004938/0348;SIGNING DATES FROM 19870625 TO 19870701

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Effective date: 19961120

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Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362